1. Field of the Invention
The present invention relates to a well locking device and double-shear shear ring, which may be used therewith.
2. Description of the Related Art
The present invention constitutes an improvement over prior well locks and in shearable retaining means that may be used in the setting and removal of those well locks.
Conventional well locks include selective locks and no-go locks. Selective locks utilize a specific type of profile in a portion of a well bore location at which the well lock is to be set. The well bore is cut to receive matching keys in the well lock for locating the well lock within a desired downhole portion of the well bore. When the well lock is lowered into the portion of the well bore having the proper profile, the well lock keys will engage within the well bore profile to engage, for example, locking dogs within a locking recess in the well bore to lock the well lock in place. Selective locks are expensive and complicated and, in operation, may have mechanical difficulties or other drawbacks.
Generally more reliable than selective locks are no-go locks, which typically incorporate a no-go landing shoulder in both the well bore and a portion of the well lock housing body, itself. When the well lock is lowered into the well bore, the no-go shoulder on the well lock housing abuts the no-go shoulder in the well bore preventing further downhole movement of the well lock body. The well lock is thereby positioned in the desired locking position for engaging the locking dogs, for example, within corresponding locking recesses of the well bore to engage the well lock in the desired downhole position of the well bore. However, when the no-go landing profile is provided on the well lock housing body, downward pressure against the well lock may be borne by the no-go landing shoulder and the well lock body housing, not by the locking dogs of the well lock, which may be stronger than the well lock housing. Providing the no-go shoulder on the well lock housing may, therefore, create undesirable high bearing stresses on a portion of the well lock housing or may have additional drawbacks. A shearable no-go shoulder has been used so that, once the well lock is positioned in the well bore and the locking dogs engaged, the shearable no-go shoulder on the well lock body can be sheared by additional downward force to relieve operating stresses from the well lock body, which may be advantageously borne by the locking dogs. Similarly, retractable no-gos have been provided that retract from engagement of the no-go in the well bore upon setting of the locking dogs. However, use of such complicated retractable and shearable no-go shoulders could be expensive, may prevent complications upon removal of the well lock from the well bore, and may otherwise be undesirable in certain applications. Accordingly, removing the no-go landing shoulder from the well lock housing body may be desirable in certain applications.
No-go locks are typically operated in multiple modes. For example, in a running mode, the locking dogs of the well lock are withdrawn within the well lock housing to allow the well lock to run freely within the well bore. In a locking mode, the locking dogs may be engaged within a recess in the well bore by use of a setting wedge associated with the well lock to force the locking dogs into the recess of the well bore, thereby setting the well lock and locking it in place within the desired downhole portion of the well bore. Thereafter, in a pulling mode, the locking dogs may be disengaged from within the recesses of the well bore so that the well lock can be removed from the well bore. The modes of operation may typically be provided by use of multiple shear pins provided in connection with: the well lock housing and running tool that is used to position and set the well lock within the well bore; the setting wedge that is used to set the well lock within the well bore and a first location on the well lock housing; and the setting wedge and a second location on the well lock housing.
In operation of a typical well lock having multiple shear pins, a first shear pin may be provided on the running tool to initially attach the running tool to the lock housing to permit lowering of the well lock within the well bore by use of the running tool; a second shear pin may be provided in a first location on the well lock housing to prevent the setting wedge from engaging the locking dogs and thereby setting the well lock prior to proper positioning; and a third shear pin may then be provided at a second location on the well lock housing to lock the setting wedge in place within the well lock housing when the locking dogs are engaged to maintain the locking of the well lock within the well bore. However, use of multiple shear pins may provide unnecessary complications, and may require the use of garter springs and other elements that could be prone to failure. Accordingly, use of multiple shear pins may be unreliable in certain applications.
The present invention may overcome one or more of any shortcomings that may be present in the prior systems.